This invention relates to small, but fully electromagnetic, circuit breakers.
Many electrical circuit interrupters of the fuse or thermal type have a long, cylindrical shape. These long cylindrical fuse or thermal circuit protectors are widely used to protect domestic appliances and many other electrical items.
It is an object of this invention to provide a circuit breaker of the electromagnetic type having an outside, generally cylindrical envelope configuration and generally of a size which is similar to the previously known fuse or thermal protectors.
It is a further object to provide such an electromagnetic circuit breaker which will open the circuit after a time delay period at certain electrical conditions and substantially instantaneously at other, electrical current conditions.
The size of the intended unt is one in which the housing will be about 3/4 inch (about 1.9 km) in maximum outside diameter and the overall length, including terminals, is about 2 inches (about 5.08 cm) long. Hence, the size of the electromagnetic coil is limited to one of relatively few turns because of the small overall size of the circuit breaker, and, since the current involved is low, about 20 amperes or less, the magnetic force produced will be low relative to a larger size circuit breaker. Thus, it is a further object of this invention to provide a mechanical arrangement for utilizing a low electromagnetic output to trip open the circuit breaker contacts.
A still further object is to provide a simplified linkage mechanism for an electromagnetic circuit breaker for use in a long, cylindrical housing.
As is well known, time delay tubes have been used in electromagnetic circuit breakers to provide a time delay, on certain electrical conditions, before the contacts are opened. In order to minimize the number of parts, it is another object of this invention to use the time delay tube as a part of the linkage mechanism for manually opening and closing the circuit breaker.
It is contemplated that the circuit breakers made in accordance with this invention will be rated at about 20 amperes at 120 volts A.C., at about 10 amperes at 240 volts A.C., and at about 20 amperes at 32 volts D.C., although it is not intended to limit this invention to these particular ratings or electrical conditions.